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Old-House Online » Old-House Tips, Restoration Stories, & More » Repairs & How To » How To Repair a Doorknob

How To Repair a Doorknob

When vintage doorknobs stop working, knowing how to troubleshoot common problems can make them good as new again. By Bill Rigby

    To repair old doorknobs and locks, start by learning a few key parts.

    To repair old doorknobs and locks, start by learning a few key parts.

    QMy old house has lots of stuck doorknob mechanisms on both interior and exterior doors. Is there an easy fix?

    ABill Rigby: No one gives much thought to doorknobs or their accompanying mechanisms until they stop working. But once you understand a bit about the anatomy of door hardware, you can perform many fixes yourself.

    On most door locks, there are two bolts that come through the face. The bolt with the slanted end is called a latch bolt, and it’s activated by turning the knobs; an internal spring retracts it when the door closes. The slant on the latch bolt rides up the lip of the strike (located on the door jamb) until the bolt falls into a hole in the strike. It provides minimal security designed simply to keep the door shut. If there’s a second rectangular bolt, it’s the deadbolt, which must be extended and retracted manually by turning a key or thumb turn, and offers a bit more security.

    If you have a door problem, the lock may not always be to blame. When houses settle, the strike may no longer align with the bolts, or the hinges may have come loose, resulting in a door that won’t stay closed. Also check for paint buildup—many locks and hinges can be hindered by coats of paint.

    If bolts no longer work and the paint’s not at fault, remove the lock and investigate further. Remove the knobs by undoing the small screw on the side of the knob shank (don’t lose it!). Once the screw is removed, the knob will either pull off or unscrew from the spindle (the 5⁄16″ square iron rod connecting the two knobs). The other knob can remain on the spindle, but as you push the spindle through the door, spacer washers may fall out—save these, too. If there is a thumb turn plate, remove that, too.

    With the knobs out, now is the time to remove the two screws from the lock’s face. You may need a heat gun to warm and release any paint. If it won’t release easily, insert the spindle or a screwdriver through the knob hub, and rock it gently to ease the lock out of the mortise. Open the lock by removing the screw(s) holding the cover in place, then snap a picture or two or make a sketch of what you see to help with reassembly. Look for broken parts anywhere in the lock. These may be small, but they are critical; set them aside. Any misshapen or broken parts may need to be repaired or replaced.

    Once opened, the lock reveals springs that may need repair.

    Once opened, the lock reveals springs that may need repair.

    You’ll also need to measure and record details of the knob hub (the casting with the square hole that holds the spindle), the spacing (the vertical distance from the center of the hub to the center of the round part of the keyhole), and the backset (the horizontal distance from the center of the round part of the keyhole to the face of the lock or door edge). Most locks came with various backsets and spacings, so these measurements are critical for getting the right internal parts.

    Most doorknob problems start with a broken spring. (The remaining problems stem from someone fixing the lock incorrectly, installing the wrong spring, or installing it improperly.) Springs break because they are fatigued or the lock was never lubricated.

    It’s possible to get some spring stock from a hardware store and make new springs yourself. An antique hardware specialist can make you new springs for about $20, or may have a supply of parts to replace broken ones. You can have the lock straightened, cleaned, and lubricated, too. For an additional fee, the lock face can be restored to its original finish. If you need parts, you’ll need some important information. Search for a maker’s name or a number cast into the body of the lock; a three- or four-digit number refers to a catalog number. (A number on the face usually refers to a key.) That and your picture of the open lock should be enough for a professional to analyze the problem.

    Once the lock’s parts are all in working order, apply a little lightweight grease on the hub’s ears and medium lubricating oil on any other moving parts. Get the oil from any hardware store—don’t use WD-40, as it is not a lubricant. Use oil sparingly, and don’t lubricate the deadbolt, as oil here tends to transfer to the key, and you don’t want an oily key in your pocket. Graphite has always been a favorite of locksmiths for smaller moving parts, although it won’t prevent rusting like oil does. Pop the cover on and try the knob and key; the lock should be working.

    Before reinstalling the lock, take the opportunity to clean up the door edge, knobs, and escutcheons. Then press the lock back into the mortise and replace the screws. Next, install the knobs—alignment is key; the spindle must remain perpendicular to the door face for maximum lifespan of the whole assembly.

    Then install the knobs and replace the spacer washers. Make sure everything fits tightly—loose knobs wear out the escutcheons, loose escutcheons wear out the hubs, and worn hubs won’t work the latch bolts. Finally, reset the strike so the holes line up with the bolts, adjusting the strike mortise in the jamb if necessary.

    Online Exclusive: Need new doorknobs? Check out our guide to 6 classic styles.

    Published in: Old-House Journal December/January 2013

    { 11 comments… read them below or add one }

    Edward October 28, 2012 at 2:16 pm

    Thanks for the instructional. Sticky doorknobs and doorjambs are one of my pet peeves, and I used to always chalk it up to bad engineering. But you’ve not only elucidated the real problems with stubborn door hardware, but given practical, frugal ways to fix them.

    Lou Giovannetti October 30, 2012 at 3:48 pm

    I have subscribed to your magazine over a month ago and have not received a magazine or confermation of the subscription?

    Carleen October 30, 2012 at 10:29 pm

    How do I get the door open so that I can remove the latch assembly?

    Vancouver Glass November 29, 2012 at 3:02 pm

    It is indeed important to know how to properly choose a replacement door knob when needed.

    RKT December 5, 2012 at 4:14 pm

    How do I find a replacement key? I have a 1940 brick rambler with vintage indoor mortised locks, but only one key. All locks are the same, but no one knows how to duplicate the key.

    Sherry December 5, 2012 at 5:03 pm

    I have taken apart most of the door latches and locks in our 1918 house to clean or repair. I love the way these old mechanisms work.

    LindaG December 23, 2012 at 8:13 pm

    Is there a way to date a mortise lock? I have one that is almost identical to the one shown in your article, but very little in the way of identification.
    There is a W stamped on the cover. And E3 in a circle inside, and the number 2327. There is no key number.

    I have another mortise lock, with the name Penn, I believe, on the outside.
    Is has Pat. Nov 5 1912 on the inside, so I think that one may or may not have been made then.
    It has a lock number 5511 on the inside and the letters or initials L J on the deadbolt. This one does not have a key number inside either, that I have been able to find.

    Thanks for your very interesting article.

    Greta March 10, 2013 at 10:15 pm

    I would never use grease or oil on the inside of a mortise lock of this type and age because the keyhole is always open which would attract dust and lint to the moving parts rather quickly-making the problem worse.

    Donna Kerr July 18, 2013 at 11:56 am

    I need repalcement key for a PENN lock ? Any ideas?

    Dona Boley November 27, 2013 at 5:23 pm

    My door knobs are stuck on the spindle. All set screws have been removed but knobs won’t pull off or unscrew.

    Joel Garreau July 26, 2014 at 5:24 pm

    Re removing the door knob. After loosening the set screws, try unscrewing it from the spindle. Worked for me. Found this tip and others here: http://www.instructables.com/id/Cleaning-and-Repairing-an-Antique-Mortise-Door-Loc/

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